Inserting an SD-card on an Intel NUC10i3FNK4 (which contains a GL9755)
results in the message:

    mmc0: 1.8V regulator output did not become stable

Following this message, some cards work (sometimes), but most cards fail
with EILSEQ. This behaviour is observed on Debian 10 running kernel
4.19.188, but also with 5.8.18 and 5.11.15.

The driver currently waits 5ms after switching on the 1.8V regulator for
it to become stable. Increasing this to 10ms gets rid of the warning
about stability, but most cards still fail. Increasing it to 20ms gets
some cards working (a 32GB Samsung micro SD works, a 128GB ADATA
doesn't). At 50ms, the ADATA works most of the time, and at 100ms both
cards work reliably.
Signed-off-by: Daniel Beer <dlbeer@gmail.com>
Acked-by: Ben Chuang <benchuanggli@gmail.com>
Fixes: e51df6ce ("mmc: host: sdhci-pci: Add Genesys Logic GL975x support")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210424081652.GA16047@nyquist.nevSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>